1. Field of the Invention
The present invention relates to a motion determining apparatus, a motion determining method, and a picture information converting apparatus.
2. Description of the Related Art
In a picture signal converting apparatus that converts an input digital picture signal into a picture signal with a different scanning line structure or in a picture process using a highly efficient code for compressing a digital picture signal, a motion determining process for determining whether or not a considered portion of a picture has a motion is used. In a conventional motion determining apparatus, the sum of the absolute values of differences between a picture portion (for example, a block of one frame) of one frame and the same picture portion of an adjacent frame. When the sum is larger than a predetermined threshold value, it is determined that the picture portion has a motion. In contrast, when the sum is equal to or smaller than the predetermined threshold value, it is determined that the picture portion does not have a motion.
In the conventional motion determining process, since differences between adjacent frames are used, when a telop (television opaque projector) is moving, it may not be correctly detected as a moving picture. A telop is a sequence of characters and/or symbols superimposed with a picture. For example, when a character is horizontally moved, if one character element thereof overlaps with another character element one frame later, in a middle field of the frame, even if the current picture largely varies from a picture of a chronologically preceding field, since frame differences are small, the current picture is determined as a still picture. If a picture process is performed corresponding to the determined result, the smooth motion of the picture is lost. Thus, the processed result becomes unnatural. On the other hand, when a still picture is processed as a moving picture, the resultant picture becomes dim.
An object of the present invention is to provide a motion determining apparatus, a motion determining method, and a picture information converting apparatus that allow a motion determining process for an artificial picture such as a telop to be separately performed from a motion determining process for other than a telop so as to properly perform a motion adaptive process.
A first aspect of the present invention is a motion determining apparatus for detecting a motion of a partial picture of an input picture signal, comprising a first motion detecting portion for comparing a frame difference detected for the partial picture with a predetermined threshold value and determining that the partial picture has a motion when the frame difference is larger than the threshold value, a second motion detecting portion for comparing a frame difference detected for the partial picture with a predetermined threshold value, comparing a field difference detected for the partial picture with a predetermined threshold value, and determining that there is a motion of an artificial picture when the frame difference and the field difference are larger than the respective threshold values, and an output portion for forming motion determination data with determination data that is output from said first motion detecting portion and said second motion detecting portion.
A second aspect of the present invention is a motion determining method for detecting a motion of a partial picture of an input picture signal, comprising the steps of (a) comparing a frame difference detected for the partial picture with a predetermined threshold value and determining that the partial picture has a motion when the frame difference is larger than the threshold value, (b) comparing a frame difference detected for the partial picture with a predetermined threshold value, comparing a field difference detected for the partial picture with a predetermined threshold value, and determining that there is a motion of an artificial picture when the frame difference and the field difference are larger than the respective threshold values, and (c) forming motion determination data with determination data that is output at steps (a) and (b).
A third aspect of the present invention is a picture information converting apparatus for converting an input picture signal into a plurality of output picture signals with different scanning line structures, comprising a first data selecting means for selecting a plurality of first pixels of the input picture signal, the positions of the first pixels being present in the vicinity of pixels of an output picture signal to be generated, a second data selecting means for selecting a plurality of second pixels of the input picture signal, the positions of the second pixels being present in the vicinity of pixels of an output picture signal to be generated, a third data selecting means for selecting a plurality of third pixels of the input picture signal, the positions of the third pixels being present in the vicinity of pixels of an output picture signal to be generated, a memory means for storing pre-obtained estimation expression coefficients, a signal generating means for generating pixels of an output picture signal with the plurality of first pixels selected by said first data selecting means and a linear estimation expression of the estimation expression coefficients, a class determining means for forming a spatial class corresponding to the plurality of second pixels selected by said second data selecting means, forming a motion class corresponding to the plurality of third pixels selected by said third data selecting means, and supplying the estimation coefficients to said signal generating means corresponding to class information as a combination of the spatial class and the motion class, a scanning line structure converting means, connected to said signal generating means, for converting the input picture signal into an output picture signal with a designated scanning line structure, and a motion determining portion for forming the motion class, wherein said motion determining portion has a first motion detecting portion for comparing a frame difference detected for the partial picture with a predetermined threshold value and determining that the partial picture has a motion when the frame difference is larger than the threshold value, a second motion detecting portion for comparing a frame difference detected for the partial picture with a predetermined threshold value, comparing a field difference detected for the partial picture with a predetermined threshold value, and determining that there is a motion of an artificial picture when the frame difference and the field difference are larger than the respective threshold values, and an output portion for forming motion determination data with determination data that is output from said first motion detecting portion and said second motion detecting portion.
According to the present invention, since a motion detecting process for an artificial picture such as a telop is separately performed from a motion detecting process for other than a telop, the motion of the telop and so forth can be accurately detected. Thus, when the motion adaptive process is performed, the resultant picture can be prevented from deteriorating.
According to the picture information converting apparatus of the present invention, classes are detected corresponding to a plurality of pixels of an input picture signal. Pixel values are generated with estimation predictive expressions that are optimum for the individual classes. Thus, the picture information converting apparatus can generate a still picture and a moving picture with higher picture quality than the conventional apparatus. In addition, motion information is placed in class information. Thus, it is not necessary to determine whether the current picture is a still picture or a moving picture. In addition, it is not necessary to perform a switching operation of the apparatus corresponding to the detected result. Thus, the difference of the picture quality in the switching operation can be prevented. In addition, the picture quality can be remarkably suppressed from deteriorating against a motion detection error.
The following prior art references have been filed by the applicant of the present invention.
(1) Japanese Patent Application No. H09-115437 (US application corresponding thereto is now pending);
(2) Japanese Patent Application No. H10-209346 (US application corresponding thereto is now pending); and
(3) Japanese Patent Application No. H10-228221 (US application corresponding thereto is now pending).
These and other objects, features and advantages of the present invention will become more apparent in light of the following detailed description of a best mode embodiment thereof, as illustrated in the accompanying drawings.